The invention relates to a rotary potentiometer comprising a cylindric or partially cylindric resistance track whose two edges parallel to the cylindric axis are provided with at least one pair of electrodes applying voltage to the resistance track, and comprising a tap which contacts the resistance track and is fixed to an adjusting component which is rotatable around the cylinder axis.
Such a rotary potentiometer is described in EP No. 0 157 666 A1. With this rotary potentiometer an angular position of a rotatable element, for example a machine part, can be detected. For this purpose the element is coupled with the adjusting component. If a linear movement of the element is to be detected as well, not only a shifting potentiometer but also a complicated coupling mechanism is necessary for transferring the rotation only to the rotary potentiometer and the linear movement to the shifting potentiometer.
DE-AS No. 23 17 144 describes a device for adjusting several resistors by an adjusting lever slewably positioned by means of ball. Thus, shifts of the adjusting lever in xy-direction can be detected, but not movements around its longitudinal axis. A similar device is described in DE-OS No. 21 62 853.
For the detection of rotating and shifting movements arrangements working without contact are known, for example electrodynamic systems such as differential transformers, inductive or capacitive devices as well as pneumatic dynamic pressure arrangements. With such arrangements, however, a lot of wiring is required. In addition, the achievable signal voltages or signal currents are very small in comparison with the distribution voltage or distribution current. This makes such arrangements susceptible to trouble.